This invention relates to a tandem arrangement of internal combustion engines having crankshafts that are selectively coupled together by a clutch such that, when coupled, the torque developed by both engines is delivered to a transmission and thence to other propulsion machinery such as wheels and, when the clutch is disconnected, only one engine operates to deliver torque to the transmission. The tandem arrangement of internal combustion engines is intended to meet the demand for adequate power during acceleration of the vehicle and good fuel economy at highway speeds which can be sustained over a period of time at relatively low power requirements.
The demand for more fuel efficient vehicles has brought about a substantial reduction to the weight of the vehicle and, hence, also in most instances, the size of the vehicle. A smaller internal combustion engine in terms of its physical size and power output can propel such a vehicle with greater fuel economy. However, such a vehicle may not adequately perform under conditions imposing heavy demands for power. Conditions where this occurs include using the vehicle for towing purposes, accelerating particularly in a region of hilly terrain. To meet the need for increased power, it is known to modify the operation of a V-8 internal combustion engine such that at reduced power requirements, the engine operates on only six cylinders or even on only four cylinders. Recent developments on this idea include the use of a device to disable the valves for certain selected cylinders to reduce the number of cylinders that are operative. During the time when less than all of the cylinders of the engine are operative, friction by the moving pistons in the cylinder walls, bearings and the like is seen to have an adverse effect on the efficient operation of the engine. This invention seeks to overcome the foregoing disadvantages and shortcomings of known uses of internal combustion engines for a vehicle.